High-temperature alloys



Patented Dec. 27, 1949 HIGH-TEMPERATURE ALLOYS Lee,,E."osmaniMarblehead, Mass, assignor to General vElectric Company, a corporationof New York No Drawing. Application' Novemberi, 1941,; 1

Serial="No. 78437.57

6 Claims, (01. 7541-128) 2 the gamma field'of the iron-nickel-carbonalloys similar to chromium but, to a grea er extent. A solutiontemperature. of 1050 -C. provides satisfactory results.

This application is a continuation-impartof? my; copending:applicationrserial vNo. 711, l'71, now abandoned, filedNovember-21,1946, as :a; division :1 of my applicationiserial No.;-595,486,;,filed;May 23,-.l945;=now--Patent 2,442,209, both of,which'aprgfi plications :are assigned to the samev assignee as;the.presentjinvention:

The present invention 318 "an. alloy adaptedriorzz: use. as 27.wheelmaterial insuperchargerrturbines; 5:1 and the like. 1

It is oneof the objects: of the invention'to provide .ani311103.WhiCha'dGVEIODSISUfiiCiQIIK strength from :heat treatment without;coldwor king.:

In myapplication ;Serial,;No. 595,486, Patent. 2,442,209;;therewasdisclosed an alloy;.:havinga l5. carbon-content of 0.25 to 0.35 percentp'aboutemis to :18 per centrchromium, about 12 to 14 per. cent-$2:nickel,-about 1.75 to '2.25. -per cent, molybdenumgz about 0.8 to 1.2per centtungsten; about 04 to :0.6 per centsilicon,-about-1.25.to:1-.'7,5 per centmanganese, about 0.7 to 1 .0, percentcolumbium, about 5; 0.45 per cent to 1.20 per cent. beryllium,with::the;;- balance iron;

The :present-invention-is basedwinipa-rtpnzthe la-rly useful alloy(alloy comprising a discoverythatdn order-to'obtainiamalloy. of theMiture f alpha and desiredutyperit isnotanecessary toholdftheprconsisting of 0.30 per cent carbon, 17 per cent portions of certain ofthe elements, particularlmi; chromium 13 pericent nickel 2 per centmolyb' the nickel; --within'the limits: .prescribedsin my um, 1 per centtungsten, 0.5 per cent silicon, application Serial 'No. 595386,? Patent:2,442209. More specifically I havewfoundgthat ,an'zalloy which :will:developisufficient ,strengthzfromzheat s: treatmentwithout-.coldcworking may contain: from 0.25 :to 20.35 per cent carbon;n-abouterlfi "to 20 .percent chromium, about-r1210 $3.6 :per; cent rtemper t r a ov .1109. 1150*'C. there appears grain boundary fusion o ahigher rupture strength.

Although the maximumahardness in the alloy is obtainedwith an agingtemperature of 500 C., I generally employ an aging? temperature of 650C. since that is usuallyiheumaximum oper ating temperature ofsupercharger bucket wheels.

stantial softening takes place.,

cooled, are as follows:

Above 500 C. the hardness progressively decreases although-.no'considerabledecrease is; found up to:700" C. However,'at'800 (3-1a sub-cIf a. higher solution tem- .peratureeis employed,gforvexample a solutiona C. for" example aboutto be a tendency toward f th y. 11m.w 9 verselyafiects the ductility, and also the'yield 0.,strength and rupture,strength of the alloy. The

lower solution temperature, of 1050?, C. avoids this difficulty andalsqprovides' material having 1.5 per cent manganese, 0.8 per centcolumbium, and :1 per cent beryllium with the balance iron, in etheform-of forged bars which have been heated-at 1050" C. for one hour,water quenched andiaged at *650'-C.-for- 15 hours and then-aim;

nickel, about 1.75 to 2.25 per cent molybdenum;

about 0.8 to 1.2 percent tungstemaaboutOAi to 0.6 Apmxk I jv 1 ge l ilepercent silicon:, about;-1-.0-,to 1.75,-peracent ;mane; "mate esutsganese;about:=0.7to':1;1'per centcolumbiumpabout- Bars Tested'am" 5253?"t en 0.4-5-to 1.20Jper, centziberyllium :withthedoalancea rl it-e Elong.g II'OIITI .Theralloytmayobexzforged at 2000-..21001 1'5, :1 Room Temp.134,500: 176,600 7 6.93 woos-1700 F.5In order to 'developtthecoptimum..1 2 3;}? properties in the alloy, it is quenched: fI'Om1:a;--,: I 5.57.0 temperature of about 1050-1100 C. and thereg;; after aged for about15 to 24 hours at650 C. The D0 alloy as quenched has a Rockwell Chardness of 01 i 15*to 205 After agingat 650" C. the Roekwell c hardnessis 40 and remains substantiallyconstant- Ruptl-l'miresuzts F at thatfigurezviThe alloytdoes not airqharden. m

The structure after solution treating and aging m me, 3 35? ggiggconsists 'of.a gamma solid solutionpr a mixture T. v, ofalpha and'gamma'solid solutions together with; m0 t 500, H 14: the precipitatedcompounds-"and carbides.- Pre- 1. 0 8} cipitatedcompounds.farebelievedato be complex 5 iron and :nickel beryllides; Th eratio betweeni; thealphaand gamma solidsolutions apparently depends onthe composition, the nickel-chromium ratio having a decided effect inthis respect and also the percentage of beryllium which resnickel-chromium ratio, decreases the ratio between the alphaandgamma-solid solutions or tricts eliminates the alpha-solid solution. Forexample,

Tensile ;and rupture properties of a particu- Ani increase.: inthe-nickel content of the-alloy; over that of alloy A, that is, anincrease in the each of the following alloys, after the precipitationheat treatment, are characterized by a microstructure consisting of amatrix of gammasolid solution with precipitated carbides and beryllides:

Alloy B C D E Carbon 0. 28 0. 26 0. 29 0. 27 Silicon 0. 37 0. 39 0. 410. 38 Manganese 1. 20 1. 18 1. 13 1. 57 Chrmium 17. 45 18. 33 18. 39 19.17 Nickel 16. 99 23. 76 30. 12 35. 80 Tungsten 0 96 0. 93 0.96 0. 94Molybdenum 2. l7 2. 10 2. 16 2. 19 Columbium 0. 91 1. 02 0. 96 0. 89Beryllium 1. 04 1. 02 0. 86 0. 89 Iron balance balance balance balanceTensile results Yield Tested Strength 5222% Elongn, Red Area, at-(.002/), s i Percent Percent p. s. i.

I 73, 090 150, 820 22 33.1 1200 F 108, 500 17 33. 0 T. 79, 220 141, 73017 26. 0 1200 F 106, 600 15. 5 32. 9 'I 71, 730 135, 170 21. 7 38.1 RT-83, 060 157, 250 27. 5 38. 9

Rupture results at 1200 F.

Alloy Hours Stress, p. s. i.

100 68,000 1, 000 40, 000 100 62, 000 1, 000 53, 500 100 over 70.000 1,000 48, 000 100 50, 000

The alloys B, C and D when heated to 1100 C. for 1 hour, water quenched,aged for 15 hours at 650 C. and air quenched tested as follows:

Tensile results In general, the alloys containing less than about 30 percent, i. e., from about 12 to 30 per cent, nickel are preferred from thestandpoint of optimum forgeability and high temperature strengthcharacteristics.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A heat treatable iron base alloy containing about 0.25 to 0.35 percent carbon, about 16 to 20 percent chromium, about 12 to 36 per centnickel, about 1.75 to 2.25 per cent molybdenum, about 0.8 to 1.2 percent tungsten, about 0.4 to 0.6 per cent silicon, about 1.00 to 1.75 percent manganese, about 0.7 to 1.1 per cent columbium, about 0.45 to 1.2per cent beryllium with the balance substantially all iron.

2. A heat treatable iron base alloy containing about 0.25 to 0.35 percent carbon, about 16 to 20 per cent chromium, about 12 to 30 per centnickel, about 1.75 to 2.25 per cent molybdenum, about 0.8 to 1.2 percent tungsten, about 0.4 to 0.6 per cent silicon, about 1.00 to 1.75 percent manganese, about 0.7 to 1.1 per cent columbium, about 0.45 to 1.2per cent beryllium with the balance substantially all iron.

3. A heat treatable iron base alloy containing about 0.25 to 0.35 percent carbon, about 16 to 18 per cent chromium, about 12 to 14 per centnickel, about 1.75 to 2.25 per cent molybdenum, about 0.8 to 1.2 percent tungsten, about 0.4 to 0.6 per cent silicon, about 1.25 to 1.75 percent manganese, about 0.7 to 1.0 per cent columbium, about 0.45 to 1.2per cent beryllium with the balance substantially all iron.

4. A heat treatable iron base alloy containing about 0.3 per centcarbon, about 17 per cent chromium, about 13 per cent nickel, about 2per cent molybdenum, about 1 per cent tungsten, about 0.5 per centsilicon, about 1.5 per cent manganese, about 0.8 per cent columbium,about 1 per cent beryllium with the balance substantially all iron.

5. A heat treatable iron base alloy containing about 0.3 per centcarbon, about 18 per cent chromium, about 24 per cent nickel, about 2per cent molybdenum, about 1 per cent tungsten, about 0.4 per centsilicon, about 1.2 per cent manganese, about 1.0 per cent columbium,about 1 per cent beryllium with the balance substan tially all iron.

6. A heat treatable iron base alloy containing about 0.3 per centcarbon, about 18 per cent chromium, about 30 per cent nickel, about 2per cent molybdenum, about 1 per cent tungsten, about 0.4 per centsilicon, about 1.1 per cent manganese, about 0.8 per cent columbium,about .9 per cent beryllium with the balance substantially all iron.

LEE E. OSMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,945,653 Masing Feb. 6, 19342,373,490 Mohling Apr. 10, 1945 FOREIGN PATENTS Number Country Date v392,711 Great Britain May 25, 1933

